The fuel quantity processor performs fuel measurement, system tests, and communicates with the other aircraft systems. The processor unit reads fuel quantity measurement data from tank mounted capacitance probes, densitometers, compensators, and temperature sensors. The processor samples, scales, filters, converts the data and outputs fuel quantities, fuel temperatures, and status messages to other aircraft systems. The fuel quantity processor also provides accurate, rapidly sampled data to the ground refuel panel.

Digital interfaces are typically used as the communication vehicle between the processor unit and the other aircraft systems. Many processors employ a dual architecture with separate and independent processor channels, each with dedicated communications channels. Through the use of independent processor channels and dedicated data lines, a detected failure in one processor or a failure in any single communications path will not prevent the transmission of valid fuel measurement data to any of the other aircraft systems.